But when opportunity knocks, someone needs to answer. And left-hander Bobby Poyner and right-hander Marcus Walden swung the door wide open with their respective performances amid the Red Sox’s other offseason/spring training developments. Now, they’re both expected to open the season in Boston’s bullpen despite entering camp as a couple of unknown non-roster invitees.

So, who are these guys?

Let’s start with Poyner, who figures to serve as the Red Sox’s only left-handed reliever. Fellow southpaws Robby Scott and Roenis Elias competed for the same spot, but they were optioned to Triple-A Pawtucket on Saturday. With that, Poyner’s job now seems secure despite Red Sox manager Alex Cora saying throughout the spring he’d be comfortable starting the season without a lefty reliever.

Poyner, a 14th round pick in 2015, never has pitched above Double-A, but he’s coming off a solid 2017 at the minor league level. He posted a 1.49 ERA, a 0.93 WHIP and struck out 12.5 batters per nine innings in 43 appearances spanning 60 1/3 frames split between Double-A Portland and High-A Salem.

Poyner’s stuff isn’t necessarily electric, and he’s older than most prospects, having turned 25 in December. But he creates some deception with his delivery, allowing his high-80s/low-90s fastball to play — in the minors, at least — in conjunction with a decent-looking changeup.

“I just love the fact that he has different ways of getting people out and he can get righties out,” Cora said in Fort Myers, Fla., per the Boston Sports Journal. “He’s not a — what do they call it? A LOOGY (a lefty one-out guy)? He’s a good lefty and we’re going to put him in spots where he can get people out. We’re going to talk to him about usage, certain pitches in certain situations. We feel that changeup can play and he can use that to lefties and righties.”

Scott seemed to have the inside track on a spot in Boston’s bullpen as a left-hander with major league experience who held lefties to a .121 batting average last season, but he struggled this spring while Poyner posted an 0.87 ERA and a 0.48 WHIP with eight strikeouts across 10 1/3 innings.

“Obviously as camp got later, started to think about it a little bit,” Poyner told reporters in Fort Myers, per MassLive.com, of making the roster. “But I tried to remain realistic the whole time and just really come to the field every day and continue to work on my pitches because I knew working on my pitches was really what was going to help me move forward.”

While Poyner’s spring ascent was surprising, Walden’s inclusion on Boston’s Opening Day roster is even more stunning. He spent time in Pawtucket’s rotation and bullpen last season, going 10-6 with a 3.92 ERA in 29 appearances (15 starts). But the former ninth-round pick of the Toronto Blue Jays seemed more like an organizational depth guy upon arriving at camp, especially with the Red Sox having other veteran options, including right-hander Brandon Workman, who was demoted over the weekend after a shaky spring.

Walden, at age 29 and three years removed from independent ball, was a long shot to say the least. But his production — 0.69 ERA, 0.77 WHIP and 15 strikeouts in 13 innings — caught the Red Sox’s eye, and now he’s positioned to make his first major league appearance for Boston after spending time with four other organizations in addition to his stint with the Lancaster Barnstormers of the Atlantic League.

“I was in independent ball in 2015,” Walden said, per MassLive.com. “And I honestly called my wife (Nichole) one day in June. Told her, ‘If you want me to come home and quit, I’ll go home and go to school and get a job. She told me, ‘Not a chance.'”

It remains to be seen how long Poyner and/or Walden remain with the Red Sox. Drew Pomeranz, Eduardo Rodriguez and Steven Wright — all beginning the season on the 10-day disabled list — will return before long, likely forcing left-hander Brian Johnson, who’s out of minor league options, to Boston’s bullpen in the process. Relievers Tyler Thornburg and Austin Maddox also are working back from injuries, and Workman remains very much in the conversation moving forward. Not to mention, second baseman Dustin Pedroia’s eventual return could create another roster logjam.

But various circumstances, including performance, created some camp competition and ultimately led to a couple of surprise additions to the Red Sox’s Opening Day roster, which will be tasked with getting Boston off on the right foot for 2018.

“They won it,” Cora said of Poyner and Walden. “They pitched well. They did an outstanding job throughout spring training.

“You talk about spring training stats and you get caught up, but it’s not about the numbers. You see the stuff, the way they went after the hitters, the weapons, the pitches they can use. We feel like they can help us out right now.”